Re: Functional issues of cyclic dependencies

From:

Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 06 Feb 2008 11:24:44 -0800

Message-ID:

<47aa0986$0$32560$7836cce5@newsrazor.net>

Jack wrote:

Kevin McMurtrie a 9crit :

In article <47a851f1$0$847$ba4acef3@news.orange.fr>,
Jack <mlskqd@poqsd.com> wrote:

Hi,

i've read some articles on cyclic dependencies, that they are bad,
very bad. But i can't find any real example of functionnal (!=
design) issue with them.

Do you know any ?

Why would it be a functional issue? It's only a design issue in that
the complexity of maintenance can become unmanageable. For a small
package that performs a specific task, cyclic dependencies may be a
perfectly elegant design. When cycles go beyond the package scope,
you increase the risk of overlapping cyclic references prohibiting any
changes to the code (spaghetti code).

That's the most persuasive point i've read.

But still, when i modify a method, i must check all the call sites.
Whether the call sites are in the same package doesn't change the
difficulty, from my experience.

Right, but if you need to change class A, but it affects class B, which
affects class C, which in turn affects class A, whoops have to change B
again. It becomes difficult to effect change in cyclic dependencies.
Once you notice cyclic dependencies getting out of control, you can
easily decouple elements with an event system.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>